In weed management, repeating the same thing over and over can lead to different results. When growing the same crop and using the same herbicide in a field year after year, it creates a pattern of conditions that yield-robbing weeds can adapt to and survive. Resistance to herbicides develops when weeds are allowed to adapt to weed control methods.
“The challenge is certain species — in particular here in the Midwest, the Amaranthus species — continue to evolve resistance to herbicides,” says Aaron Hager, University of Illinois Extension weed scientist. “If there's not anything new and novel regarding new herbicides being introduced, the challenges are really around what remains effective that a farmer can depend on and rely upon? The answer is, every year, it just becomes less and less. Fewer herbicides are effective. What we know about resistance in Amaranthus is once it's established in a field’s weed population, it doesn't go away.”
Fight weed resistance
Iowa State University research shows waterhemp can cause corn yield loss as high as 20%, depending on weed density.
With herbicide products that have multiple effective sites of action (SOAs), weeds are not as likely to get comfortable. This can be maximized in a crop rotation. A strong weed management program in corn can improve a soybean weed control program in the same field next season, because the rotation should make it easier to choose different herbicide groups for the different crops.
“By switching up your crop and then switching up your site of action, you are helping control weeds in your field this season and delaying resistance issues,” explains Randy Kool, Syngenta agronomy service representative based in Iowa.
A cycle of crop rotation and herbicide applications with multiple effective SOAs fights tough weeds and helps prevent resistance over the long term. Weeds are less likely to adapt to the patterns created around either crop or use of single SOAs.
Harvest more bushels
A strong weed management program can help a grower harvest more bushels at the end of the year, Kool says. “If you’re planting corn, consider Acuron corn herbicide, with three effective sites of action and four active ingredients, including the exclusive active ingredient bicyclopyrone. It is proven to deliver 5 to 15 more bushels per acre than any other corn herbicide when used in a preemergence application at full label rates.”
The combination of powerful weed control, long-lasting residual and proven crop safety enables Acuron to better protect corn from tough, yield-robbing weeds. “Fewer weeds mean more sunlight, nutrients and water available for a growing crop,” he notes, “which leads to more bushels and ultimately more revenue potential.”
In dicamba-tolerant soybeans, Kool recommends the latest new herbicide from Syngenta —Tavium Plus VaporGrip Technology herbicide, the market’s first premix residual dicamba herbicide. “Through the contact control of dicamba, Tavium manages the emerged weeds you see, and through the residual control of S-metolachlor, it manages the weeds you don’t see yet,” Kool says. “This powerful combination provides up to three weeks longer residual control than dicamba alone.”
Tavium is most effective when used as part of a season-long weed management program. Kool adds, “An integrated approach can help reduce the weed seed bank, increase diversity within a herbicide program and fight weed resistance.”
Visit resistancefighter.com to learn more about managing resistant weeds on your farm.